No idea, sorry. With a 40mm offset on a 16" wheel, there's no problem. But a 15" wheel seems like a not so great idea. If it was me, I would just purchase some 16" steel wheels and slap the winter tires on those. Steel wheels are inexpensive...

I would not go for 15", Usually I would downsize 1" from 17", so I would go for 16". Both 215/55R16 and 205/60R16 will work very well but 215/55 is $20-30 more than 205/60 per tire. Take a look at this video.. that's for 2018 Leaf, looks good! Hope it helps.

I have a 1st generation 2017 SL and just upgraded for 215/55/R17 because the original 215/50/R17 were little thin that damage the wheel bearing often. I have noticed that the 215/55/R17 is quieter than the 215/50/R17 due to the extra 3/4" tire thickness I have gained that add more cushion. I recommend to all leaf owners to do so. Plus, you will gain 3 miles more range because of the thicker tire.